Bolts and stuff

This is just "curious" question. What do those numbers mean on bolts? 4, 7 ? Does it mean "original" kawasaki or not?
I "lost" one of the engine bracket bolts, and then I later found it. It was skipped during plating.

But while looking I searched by PN 92001-1578 and couple came up had "7" stamped. None of my bolts on engine have those numbers. Many other bolts throughout have those numbers.

Maybe it has to do with bike made here in US? Just curious..


 

I believe it's the grade of the steel.

No mark, 4, 7, 9, in order of strength and hardness.

"Maybe it has to do with bike made here in US? Just curious."

The hardware we assembled bikes with in Lincoln all came from Japan. 
Mike

Ok, so all the bolts for engine mounting don’t have numbers on them. I am sure they are original. When I lookup pn on ebay- they pop up with #7 on them 

Compared to SAE rating...

4 = grade 2
7 = grade 5
9 = grade 8

Regarding unmarked bolts, it's a crap shoot.  They could be nice and strong, just not marked.  On the other hand, they could be made of cheese.

Here is some basic info on bolt grades.

www.aptp.com/wp-content/themes/va/pdf/APTP_BoltNut-Chart.pdf

www.aftfasteners.com/grades-of-bolts-bol...bolt-strength-chart/

Many people believe higher grade is better, but not always.  Higher grade bolts will take more stress but they are more prone to fatigue failure and are not used in applications where fatigue is a design criterion.  Lower grade bolts are still very strong but they are also ductile, which makes them more suitable for fatigue or vibration applications.  The designer will put a lot of thought into which bolt to use for the intended use, and may even specify that a bolt only be used once, or maybe a limited number of times.

Speaking of those engine bolts. I was going through FSM to find proper torques and interestingly - FSM is different from parts fiche on bolt info. Perhaps it was changed during model run?

Basically, I have 4 short bolts in front of engine (2 on top and 2 on bottom) and 2 long bolts on back.
FSM shows 4 long bolts - 2 in front, 2 on back.